1. Field of the Invention
The present invention relates to a dynamic storage unit for structural components of tyres, in a plant in which said components are produced at the time of their application to a tyre being manufactured.
2. Description of the Related Art
U.S. Pat. No. 4,543,149 describes a supporting apparatus for strips of elastomeric material used for wrapping turns of bead wires of tyres. Said apparatus comprises a stationary structure-and a movable structure comprising a sequence of reels on which said strip of elastomeric material is wound. Means for joining two ends of different strips are provided on said stationary structure. The strip is unwound from each individual reel. Whenever a reel becomes empty, the end of the strip of this reel is joined to the initial end of the next reel. The movable structure moves the reels in such a way as to place them in a position for correct unwinding and in a position for facilitating the joining to the end of the preceding reel in the sequence.
A tyre for vehicle wheels normally comprises a carcass structure, essentially consisting of one or more carcass plies shaped in an essentially toroidal configuration and having its axially opposite lateral edges engaged with corresponding annular reinforcing structures incorporating circumferentially inserts, usually called “bead wires”. Each annular reinforcing structure is incorporated in what is called a “bead” which is formed along an inner circumferential edge of the tyre to secure the tyre to a corresponding fitting rim.
A belt structure comprising one or more belt strips shaped in the form of closed rings, essentially consisting of textile or metal cords suitably orientated with respect to each other and to the cords belonging to the adjacent carcass plies, is applied in a radially external position to the carcass structure.
A tread band, normally consisting of a strip of elastomeric material of suitable thickness, is also applied to the belt structure in a radially external position.
It should be noted that, for the purposes of the present description, the term “elastomeric material” denotes the mixture of rubber in its entirety, in other words the assembly formed by at least one polymeric base suitably amalgamated with reinforcing fillers and/or process additives of various types.
A pair of sidewalls is applied on opposite sides of the tyre, each sidewall covering a lateral portion of the tyre lying between what is called the shoulder area, located in the proximity of the corresponding lateral edge of the tread band, and the corresponding bead.
Given all the above, it should be noted that each type of tyre is essentially distinguished from the others by a set of chemico-physical, structural, dimensional and visual characteristics.
The chemico-physical characteristics are essentially dependent on the type and composition of the materials, particularly the recipes of the various mixtures used in the formation of the elastomeric materials. The structural characteristics are essentially concerned with the number and type of structural components present in the tyre, and their positioning with respect to each other in the tyre structure. The dimensional characteristics relate to the geometrical measurements and to the cross-sectional profile of the tyre (the external diameter, the chord or maximum width, the height of the sidewall and their ratio, in other words the section ratio), and are referred to below simply as the “specification”. The visual characteristics consist of the groove design of the rolling surface of the tread, the ornamental patterns and the various distinctive pieces of wording or signs reproduced on the tyre, for example on the sidewalls of the tyre, and are referred to jointly as the “tread design” in the remainder of the present description.
Conventional production processes essentially comprise four distinct steps in the manufacture of tyres:    a) preparation of the mixtures,    b) forming of the individual structural components,    c) assembly of the different structural components in succession, to produce a crude tyre on a drum or other suitable support,    d) vulcanization of the crude tyre with simultaneous moulding of the tread design on the outer surface of the tyre.
For the purposes of the present description, the term “type of tyre” denotes a tyre having a particular specification, specified structural components, and a specified tread design.
Patent application WO0139963 in the name of the present Applicant describes an automatic plant for producing types of tyres different from each other, comprising:                a manufacturing unit having a plurality of work stations, each designed to assemble at least one corresponding structural component on at least one type of tyre being processed,        a vulcanizing unit, having vulcanizing moulds for the types of tyres which have been manufactured,        devices for the functional transfer and movement of the tyres being processed, operating between said work stations and the vulcanizing unit.        
Each of these structural components is made directly at the time of assembly, using a semi-finished base product supplied in a predetermined quantity according to the type of tyre being processed.